The production and recovery of lube oil is an important commercial process because of the ever-present and growing demand for high quality lubricants and lubricating oil which are used particularly in internal combustion engines. Unblended lube oil stocks are usually obtained by fractionating crude oil. However, recently a growing trend is to recover and recycle spent lubricating oil to produce lube oil blending stocks which are equal to or even better than virgin lube oil stocks. This recycling of spent lubricating oil not only makes economic sense in light of dwindling crude oil supplies, but is also ecologically sound.
Those skilled in the art of petroleum refining are well versed in fractionation and process control but, despite this fact, artisans always have sought methods to minimize capital costs of equipment and facilities, and to reduce the operating costs of petroleum refineries. The process of the present invention provides a facile and economical solution for the production of a lube oil fraction having a constant, predetermined flash point.